The present invention relates to a switch for a chainsaw wherein the power cannot be engaged with the chainsaw by pushing a lever to a remote position.
A conventional switch device for a power tool generally includes a trigger which is engaged with a trigger assembly. When pulling the trigger, the circuit of the power tool is activated and the tool is operated. However, most of the triggers have no safety device to avoid the user to touch the trigger unintentionally so that it is possible that the trigger is pulled unintentionally and the chainsaw for example is running. This is extremely dangerous so that there is a need to develop a safety device to prevent the situation from happening.
In accordance with one aspect of the present invention, there is provided a clutch safety switch for a power tool and the clutch safety switch comprises a casing having a slot for a safety member slidably engaged therewith. A lug extends from an underside of the safety member and a trigger is pivotally located in the casing and has a protrusion which is interfered by the lug of the safety member. A link has an end thereof connected to the safety member. A gear is received in the casing and connected to a power source. The gear is independently mounted to an output shaft and a plurality of engaging recesses are defined in the gear. A plurality of guide rods and guide members respectively extend from an inside of the casing. A clutch member is mounted to the output shaft and has a plurality of blades each of which has a guide slot in which respective one of the a plurality of guide rods extends. Each blade has a tapered extension extending therefrom which is able to be movable along the guide member. An engaging member is movably mounted to the output shaft and has bosses extending from a side thereof. A cover is fixed on the clutch member and the engaging member is retained in a central hole in the clutch member by the cover. A link is connected between the safety member and a plate connected to one of the blades of the clutch member. The plate has an L-shaped slot so as to receive an end of the link. A spring has one end thereof connected to the plate and the other end of the spring is fixed to a rod in the casing. A lever is pivotally connected to the casing and an extension is connected to the lever. The extension has a first elongate slot and a second elongate slot. Two pins in the casing are located in the first elongate slot and a position rod extending from the plate is movably engaged with the second elongate slot.
The primary object of the present invention is to provide a clutch safety switch for a power tool wherein the clutch device disengage the power from the output shaft by pushing a lever on the casing.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.
FIG. 1 is an exploded view to show a clutch safety device of a power chainsaw of the present invention;
FIG. 2 is a side view to show the clutch safety device of the present invention;
FIG. 3 is a side view to show the clutch safety device of the present invention wherein the clutch member is rotated by sliding the safety member;
FIG. 4A shows that the engaging member is not yet moved to engage with the clutch member of the clutch safety device of the present invention;
FIG. 4B shows that the engaging member is moved to engage with the clutch member of the clutch safety device of the present invention, and
FIG. 5 shows that the link is located in a horizontal of the L-shaped slot in the plate when pushing the lever.